For over fifty (50) years automotive engine oils have been formulated with zinc dialkyl dithiophosphate (ZDDP) resulting in low levels of wear, oxidation, and corrosion. The additive is truly ubiquitous and found in nearly every modern engine oil. ZDDP imparts multifunctional performance in the areas of anti-wear, anti-oxidation, and anti-corrosion and is undeniably one of the most cost-effective additives in general use by engine oil manufacturers and marketers.
However, there is concern that phosphorus from engine oils may volatilize and pass through the combustion chamber so that elemental phosphorus is deposited on catalytic systems resulting in a loss of catalyst efficiency. ZDDP is known to provide a source of phosphorus that may cause significant problems with exhaust catalytic converters and oxygen sensors when the phosphorus from combusted oil forms an impermeable glaze that may mask precious metal catalytic sites. As a result there is pressure by the automakers to control and/or reduce the amount of phosphorus-containing compounds used in engine oils to facilitate longer converter and oxygen sensor life, and to reduce the manufacturer's initial costs of converters through lower precious metal content.
While a reduction in the phosphorus content of the lubricating oils may improve catalytic converter life or efficiency, the benefits of phosphorus additives for friction control and wear protection may not be conveniently matched by non-phosphorus containing additives. Accordingly, there is a competing need for additives and methods that enable protection of catalytic activity without significantly reducing a total phosphorus content of the lubricating oil compositions.
In one embodiment herein is presented a lubricated surface containing a lubricant composition including a base oil of lubricating viscosity, an amount of a phosphorus-containing compound, and an amount of at least one hydrocarbon soluble titanium compound. The titanium compound is effective to provide an aged catalyst temperature that converts at least fifty percent of exhaust gas hydrocarbons, carbon monoxide, and NOx that is lower than an aged catalyst temperature that converts at least fifty percent of exhaust gas hydrocarbons, carbon monoxide, and NOx of the lubricant composition devoid of the hydrocarbon soluble titanium compound.
In another embodiment, there is provided a vehicle having moving parts and containing a lubricant for lubricating the moving parts. The lubricant includes an oil of lubricating viscosity, at least one phosphorus-containing compound, and an amount of at least one hydrocarbon soluble titanium compound. The titanium compound is effective to provide an aged catalyst temperature that converts at least fifty percent of exhaust gas hydrocarbons, carbon monoxide, and NOx that is lower than an aged catalyst temperature that converts at least fifty percent of exhaust gas hydrocarbons, carbon monoxide, and NOx of the lubricant composition devoid of the hydrocarbon soluble titanium compound.
In yet another embodiment there is provided a fully formulated lubricant composition including a base oil component of lubricating viscosity, at least one phosphorus-containing compound, and an amount of hydrocarbon soluble titanium-containing agent. The titanium-containing agent is effective to provide an aged catalyst temperature that converts at least fifty percent of exhaust gas hydrocarbons, carbon monoxide, and NOx that is lower than an aged catalyst temperature that converts at least fifty percent of exhaust gas hydrocarbons, carbon monoxide, and NOx of the lubricant composition devoid of the hydrocarbon soluble titanium-containing agent. The titanium-containing agent is essentially devoid of sulfur and phosphorus atoms.
A further embodiment of the disclosure provides a method of reducing an aged exhaust catalyst temperature effective to convert at least fifty percent of exhaust gas hydrocarbons, carbon monoxide, and NOx. The method includes contacting the engine parts with a lubricant composition having a base oil of lubricating viscosity, at least one phosphorus-containing compound, and an amount of a hydrocarbon soluble titanium compound effective to provide an aged exhaust catalyst temperature that is lower than an aged exhaust catalyst temperature that converts at least fifty percent of exhaust gas hydrocarbons, carbon monoxide, and NOx of the lubricant composition devoid of the hydrocarbon soluble titanium compound.
As set forth briefly above, embodiments of the disclosure provide a hydrocarbon soluble titanium additive that may significantly improve exhaust catalyst performance despite the use of lubricant compositions containing phosphorus compounds that otherwise negatively impact exhaust catalyst performance over time. The additive may be mixed with an oleaginous fluid that is applied to a surface between moving parts. In other applications, the additive may be provided in a fully formulated lubricant composition. The additive is particularly directed to meeting the currently proposed GF-5 standards for passenger car motor oils and PC-10 standards for heavy duty diesel engine oil as well as future passenger car and diesel engine oil specifications. The additive may be particularly useful to enable vehicles to meet stringent 120,000 mile catalyst durability efficiency standards such as EPA Tier-II, BIN5.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the embodiments disclosed and claimed.